Heating device with hot water supply function

ABSTRACT

A heating device with hot water supply function includes: a combustion means; a main heat exchanger; a circulation passage connecting the main heat exchanger to an heating apparatus; a circulation pump provided in the circulation passage; a bypass passage that branches off from the circulation passage and bypasses the room heating apparatus; a secondary heat exchanger provided in the bypass passage; a cold water supply passage for supplying cold water to the secondary heat exchanger; a hot water supply passage for supplying hot water heated by the secondary heat exchanger; a hot water supply bypass passage that connects the cold water supply passage to the hot water supply passage bypassing the secondary heat exchanger; a flow adjustment means for adjusting the flow rate in the hot water supply bypass passage and thereby controlling the temperature of hot water to be supplied; and an expanded passage portion of the hot water supply passage whose diameter is increased from an intermediate portion of the hot water supply passage to its downstream end.

BACKGROUND OF THE INVENTION

The present invention relates to a heating device with hot water supply function that performs room heating by supplying heat to a room heating medium by combustion of fuel, and that also performs hot water supply by supplying heat to cold water by heat exchange with this room heating medium; and in particular relates to a heating device with hot water supply function that supplies hot water at a high flow rate by adjusting the temperature of the hot water by mixing with cold water at a low temperature.

Previously, heating devices with hot water supply function have been widely used that are capable of changing over between room heating operation and hot water supply operation. This type of heating device with hot water supply function comprises a combustion means, a main heat exchanger, a circulation passage connecting between the main heat exchanger and a room heating apparatus that is installed inside a building, a circulation pump provided in the circulation passage, a bypass passage that branches off from the circulation passage so as to bypass the room heating apparatus, and so on. A changeover means is provided at the portion where the bypass passage branches off from the circulation passage, and the changeover means is capable of being changed over so that the room heating medium flows either in the circulation passage or in the bypass passage. A secondary heat exchanger is provided in the bypass passage, and both a cold water supply passage that supplies cold water to the secondary heat exchanger, and also a hot water supply passage for supplying hot water from the heat exchanger to a hot water supply faucet or the like, are connected thereto.

By utilizing the heat of combustion from the combustion means, the main heat exchanger supplies heat to the room heating medium that flows due to the operation of the circulation pump. And during room heating operation, in order for the room heating medium to which heat has thus been supplied to be utilized by the room heating apparatus, the changeover means is changed over so that the room heating medium flows through the circulation passage. Thus, the room heating medium to which heat has been supplied flows through the circulation passage and its heat is dissipated by the room heating apparatus, and then the thermal medium returns to the main heat exchanger.

During hot water supply operation, in order for the room heating medium to which heat has been supplied to be utilized by the secondary heat exchanger, the changeover means is changed over so that the room heating medium flows through the bypass passage. Cold water supplied from the cold water supply passage is heated up in the secondary heat exchanger by exchange of heat with the room heating medium. And the room heating medium that has thus exchanged heat with cold water in the secondary heat exchanger then returns to the main heat exchanger. The heated water which is heated by the secondary heat exchanger is then supplied via the hot water supply passage to the hot water supply faucet. At this time, adjustment of the hot water supply temperature is performed via the room heating medium by adjusting the strength of combustion in the combustion means, and/or by adjusting the flow rate of the circulation pump.

Since, in this heating device with hot water supply function, adjustment of the hot water supply temperature is performed indirectly via the room heating medium, accordingly it is difficult to perform this adjustment so that the temperature of the supplied hot water does not change in response to fluctuations of the hot water supply flow rate. Due to this, the present applicant has already proposed a heating device with hot water supply function in which the hot water supply temperature is adjusted by mixing together heated water to which heat has been supplied by the room heating medium in the secondary heat exchanger, and cold water whose flow rate in a hot water supply bypass passage that bypasses this secondary heat exchanger is adjusted (refer to Japanese Patent Application 2016 146594 etc.).

Furthermore, when for example a supply of hot water is requested from the heating device with hot water supply function at a high flow rate of 40 liters per minute or higher, then the hot water flows at high speed in the hot water supply passage. Thus, there is a danger that a conduit that is incorporated in the hot water supply passage may suffer wear due to this high speed water flow and that erosion thereof may take place, so that one or more holes may open up in the conduit. For combatting such erosion, a structure is per se known and described in the cited document below in which erosion is suppressed by making one of the conduits to have a greater diameter at the junction between the two conduits, thus lowering the flow speed.

Prior patent document: Japanese Patent Publication 3,911,348

When adjustment of the hot water supply temperature is performed by mixing with cold water, if the extent of mixing with cold water is insufficient, then the hot water supply temperature becomes non uniform, and this is not desirable. Moreover, there is a danger that, due to adjustment of the hot water supply temperature on the basis of this non uniform temperature, it may not be possible to adjust the hot water supply temperature in an appropriate manner. Due to this, it is necessary to make the passage after mixing long, in order to mix the hot water to which heat has been applied and the cold water sufficiently well together. However, if a long passage is provided, then the resistance to water flow becomes large, and this is disadvantageous from the point of view of providing supply of hot water at a high flow rate.

The object of the present invention is to provide a heating device with hot water supply function that, along with being capable of adjusting the temperature of the hot water and providing hot water at a uniform temperature, also is capable of providing hot water supply at a high flow rate.

SUMMARY OF THE INVENTION

The present invention presents a heating device with hot water supply function, comprising: a combustion means; a main heat exchanger; a circulation passage connecting the main heat exchanger to a heating apparatus; a circulation pump provided in the circulation passage; a bypass passage that branches off from the circulation passage and bypasses the heating apparatus; a secondary heat exchanger, provided in the bypass passage; a cold water supply passage for supplying cold water to the secondary heat exchanger; a hot water supply passage for supplying hot water to which heat has been supplied by the secondary heat exchanger; a hot water supply bypass passage that connects the cold water supply passage to the hot water supply passage, bypassing the secondary heat exchanger; a flow adjustment means for adjusting a flow rate in the hot water supply bypass passage and thereby controlling the temperature of hot water to be supplied; and an expanded passage portion of the hot water supply passage, whose diameter is expanded from an intermediate portion of the hot water supply passage to a downstream end of the hot water supply passage.

Since, according to the present invention, the hot water supply temperature is controlled by mixing the cold water flowing in the hot water supply bypass passage whose flow rate is adjusted with the hot water heated by the secondary heat exchanger, accordingly it is possible to perform adjustment in response to change of the hot water supply flow rate, so that the hot water supply temperature does not vary. Moreover, since the volumetric capacity of the hot water supply passage is increased due to the expanded passage portion and thus the flow speed is reduced, accordingly the passage becomes substantively longer. Therefore it is possible to supply hot water at a uniform hot water supply temperature, since it is possible to perform sufficient mixing together of the hot water and the cold water in the expanded passage portion. Furthermore, since the flow resistance is lowered due to the provision of the expanded passage portion, accordingly this is beneficial from the point of view of supplying hot water at a high flow rate, and moreover the flow speed is lowered, which is beneficial for suppression of erosion.

Yet further, it is possible to provide a heating device with hot water supply function that, along with being able to provide a supply of hot water at a uniform temperature by adjusting the hot water supply temperature, can also provide the hot water at a high flow rate.

In a preferred first aspect of the present invention, the hot water supply bypass passage is connected to the expanded passage portion.

According to this first aspect, since the flow speed within the expanded passage portion is low, accordingly the mixing together of the hot water and the cold water is promoted.

Furthermore, in a preferred second aspect of the present invention, a diameter of the hot water supply bypass passage is smaller than a diameter of the hot water supply passage on an upstream side than the intermediate portion thereof.

According to this second aspect, it is possible to prevent the hot water that is flowing in the hot water supply passage from flowing in reverse through the hot water supply bypass passage.

Moreover, in a preferred third aspect of the present invention, a temperature detection means is provided in the hot water supply passage on the upstream side than the intermediate portion thereof.

According to this third aspect, it is possible to ensure that the temperature that is detected by the temperature detection means does not experience any influence from the hot water that is mixed with the cold water. Accordingly, it is possible to detect the temperature of the heated water that is outputted from the secondary heat exchanger in an accurate manner, and it is thereby possible to perform adjustment of the hot water supply temperature.

And, in a preferred fourth aspect of the present invention, a distribution means is provided in a branching portion where the bypass passage branches off from the circulation passage; and the distribution means is capable of adjusting its distribution ratio, so that it becomes possible to perform only room heating operation, or only hot water supply operation, or simultaneous room heating and hot water supply operation.

According to this fourth aspect, it is possible to utilize both room heating and hot water supply at the same time, so that the convenience is enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic figure showing a heating device with hot water supply function according to an embodiment of the present invention; and

FIG. 2 is a perspective view of a conduit, on the downstream side of a secondary heat exchanger, that constitutes a hot water supply passage.

DETAILED DESCRIPTION

Now, a concrete embodiment of the present invention will be explained.

First, the overall structure of a heating device with hot water supply function 1 according to the present invention will be explained with reference to FIG. 1.

The heating device with hot water supply function 1 performs room heating operation by circulating a room heating medium that has been heated by employing heat generated by a combustion unit 2 to a room heating apparatus (not shown in the figure) that is installed inside a building and externally to this heating device with hot water supply function 1, and that is adapted to perform warm water supply operation in which hot water (warm water) is supplied by adjusting cold water that has been heated to a set hot water supply temperature by utilizing the heat of the room heating medium.

The heating device with hot water supply function 1 comprises a combustion unit 2 which is a combustion means, a main heat exchanger 10, a circulation passage 4 that connects the room heating apparatus (H.A.) that is provided inside the building with the main heat exchanger 10, a circulation pump 11 that is provided in the circulation passage 4 on the upstream side of the main heat exchanger 10, and so on. The combustion unit 2 mixes fuel gas with air and combusts the resulting mixture. And the main heat exchanger 10 applies heat to the room heating medium by exchanging heat between the combustion gases generated by the combustion unit 2 and the room heating medium.

Moreover the heating device with hot water supply function 1 comprises a bypass passage (a first bypass passage) 12, a secondary heat exchanger 20 that is provided in the first bypass passage 12 for supplying hot water, a cold water supply passage 19, a hot water supply passage 21, and so on. The first bypass passage 12 branches off from the circulation passage 4 at the downstream side of the main heat exchanger 10 so as to bypass the room heating apparatus, and joins back to the circulation passage 4 at the upstream side of the circulation pump 11. The cold water supply passage 19 supplies cold water to the secondary heat exchanger 20. And the hot water supply passage 21 supplies hot water to which heat has been supplied by the secondary heat exchanger 20 to a hot water supply faucet or the like.

Furthermore, the heating device with hot water supply function 1 comprises a control unit 5, and the devices described above and so on, including this control unit 5, are contained inside a casing 9. The control unit 5 receives detection signals from a temperature sensor and so on that will be described hereinafter, and also controls room heating operation and hot water supply operation and so on by operating the circulation pump 11, a first distribution valve 15, and so on.

Next, the circulation passage 4 will be explained.

A first temperature sensor 13 is provided in the circulation passage 4 between the circulation pump 11 and the main heat exchanger 10, and a second temperature sensor 14 is provided in the passage 4 on the downstream side of the main heat exchanger 10. The first temperature sensor 13 detects the temperature of the room heating medium as it flows into the main heat exchanger 10. And the second temperature sensor 14 detects the temperature of the room heating medium after heat has been supplied thereto by the main heat exchanger 10.

A first distribution valve 15, which is a distribution means, is provided at the branching portion where the first bypass passage 12 branches off from the circulation passage 4. The first distribution valve 15 distributes the room heating medium, to which heat has been supplied by the main heat exchanger 10, to the circulation passage 4 and the first bypass passage 12, and its distribution ratio is adjustable.

A pressure relief valve 16 is provided between the main heat exchanger 10 and the first distribution valve 15, and relieves the pressure in the circulation passage 4. And a room heating return temperature sensor 17 that detects the temperature of the room heating medium as it returns from the room heating apparatus (terminal) is provided at the upstream side of the circulation pump 11. A supplementation passage 18 for supplementing the room heating medium is connected between the circulation pump 11 and the room heating return temperature sensor 17.

Next, the secondary heat exchanger 20 for hot water supply will be explained. The secondary heat exchanger 20 is a heat exchanger of the plate type, and is provided in the first bypass passage 12. In a plate type secondary heat exchanger 20, one or more passages are formed between a plurality of heat exchange plates that are laminated together. Within the secondary heat exchanger 20, the room heating medium and cold water that is supplied from the cold water supply passage 19 flow without mixing together through respective passage each between heat exchange plates that are arranged so as to oppose one another, without mutually mixing together. Roughnesses are formed on these heat exchange plates, in order to enhance the heat exchange efficiency by increasing their surface areas.

Next, the cold water supply passage 19 and the hot water supply passage 21 will be explained.

A second distribution valve 23, a flow rate adjustment valve 24, a hot water supply flow rate sensor 25, and a cold water input temperature sensor 26 are provided in the cold water supply passage 19. The second distribution valve 23 distributes cold water to the cold water supply passage 19 and to a hot water supply bypass passage (a second bypass passage 22) that is branched off from the cold water supply passage 19 at the second distribution valve 23, and its distribution ratio can be adjusted. The second bypass passage 22 connects the cold water supply passage 19 to the hot water supply passage 21, so that the secondary heat exchanger 20 is bypassed.

Accordingly, the second distribution valve constitutes a flow adjustment means that adjusts the flow rate of the cold water flowing in the second bypass passage 22. Moreover, the flow rate adjustment valve 24 adjusts the flow rate of the cold water entering the second distribution valve 23. And the hot water supply flow rate sensor 25 detects the flow rate of the cold water that has thus been adjusted. Furthermore, the cold water input temperature sensor 26 detects the temperature of the cold water entering the second distribution valve 23.

As shown in FIGS. 1 and 2, the hot water supply passage 21 comprises a passage portion 21 a that connects to the secondary heat exchanger 20 and an expanded passage portion 21 b that extends from an intermediate portion M of the hot water supply passage 21 (the downstream end of the passage portion 21 a) to the downstream end of the hot water supply passage 21, and that is of a greater diameter than the passage portion 21 a. Accordingly, the volumetric capacity of the hot water supply passage 21 is increased by this expanded passage portion 21 b. The downstream end of the second bypass passage 22 joins to the expanded passage portion 21 b at a junction C. The passage portion 21 a that is the portion of the cold water supply passage more to the upstream side than the intermediate portion M may, for example, be built as a conduit member whose external diameter is 16 mm, while the expanded passage portion 21 b may, for example, be built as a conduit member whose external diameter is 22.2 mm. And the second bypass passage 22 may be built as a conduit member of smaller diameter than the conduit member that constitutes the passage portion 21 a, and may, for example, be built as a conduit member whose external diameter is 12.8 mm. It should be understood that these conduit members are copper tubes with wall thickness of around 1 mm.

The downstream end E of the expanded passage portion 21 b is connected to a hot water supply fitting 21 c. Thus, the hot water supply passage 21 is connected via this hot water supply fitting 21 c to a passage that leads to a hot water supply destination that is external to the heating device with hot water supply function 1.

An output hot water temperature sensor 27 is provided to the passage portion 21 a, and serves as a temperature detection means. This output hot water temperature sensor 27 detects the temperature of the hot water that is outputted from the secondary heat exchanger 20. The output hot water temperature sensor 27 and the junction C are spaced apart from one another so that, around the time when the hot water whose output temperature has been detected by the output hot water temperature sensor 27 reaches the junction C, the adjustment of the distribution ratio of the second distribution valve 23 may be completed on the basis of the temperature of this output hot water that has been detected.

A supplied hot water temperature sensor 28 is provided at the downstream side end portion of the expanded passage portion 21 b. This supplied hot water temperature sensor 28 detects the supply temperature of the hot water that has resulted from mixing together of the hot water to which heat has been applied by the secondary heat exchanger 20 and the cold water flowing through the second bypass passage 22.

Next, the control unit 5 will be explained.

While the details are not shown in the figures, the control unit 5 is capable of receiving detection signals from temperature sensors and so on that are provided within the heating device with hot water supply function 1, and moreover is connected so as to be capable of controlling the circulation pump 11 and the first distribution valve 15 and so on. Furthermore, it is connected to an operation terminal (not shown in the figure) that is provided inside the building, so as to be capable of communicating therewith.

Next, the operation and the beneficial effects of this heating device with hot water supply function 1 will be explained.

When room heating operation is started by operation of the operation terminal, the control unit 5 combusts fuel gas in the combustion unit 2. Moreover, the circulation pump 11 is operated and the room heating medium is circulated, while the first distribution valve 15 is adjusted so that the room heating medium is only circulated through the circulation passage 4. Due to this, heat is supplied by the heat exchanger 10 to the room heating medium by utilizing the combustion heat produced by the combustion unit 2. And, due to room heating operation being continued, the room heating medium is circulated at a predetermined temperature while heat is being supplied thereto.

And hot water supply operation is started when, due to a faucet such as a hot water faucet or the like being opened, the hot water supply flow rate sensor 25 detects a flow rate greater than or equal to some predetermined flow rate. When room heating operation is not being performed at this time, the control unit 5 causes fuel gas to be combusted in the combustion unit 2. Moreover, along with the first distribution valve 15 being adjusted so that the room heating medium circulates only through the first bypass passage 12, also the circulation pump 11 is operated and the room heating medium is circulated. Due to this, heat is supplied by the main heat exchanger 10 to the room heating medium by utilizing the combustion heat that is being provided by the combustion unit 2. And the room heating medium to which heat is thus being supplied exchanges heat with cold water in the secondary heat exchanger 20, thus supplying heat to that cold water and warming it up.

In order to adjust the temperature of the hot water to which heat is thus being supplied by the secondary heat exchanger 20 to the set hot water supply temperature by mixing in cold water thereto at a low temperature, the control unit 5 adjusts the distribution ratio of the second distribution valve 23 on the basis of the output hot water temperature as detected by the output hot water temperature sensor 27, and on the basis of the hot water supply temperature detected by the supplied hot water temperature sensor 28 and so on. Since the junction C and the output hot water temperature sensor 27 are separated apart from one another, accordingly the output hot water temperature detected by the output hot water temperature sensor 27 does not experience any influence from the cold water which is at a low temperature. Accordingly, the hot water to which heat has been supplied by the secondary heat exchanger 20 and the cold water passing through the second bypass passage 22 can be mixed together at the junction C in a ratio which is adjusted by the second distribution valve 23 to be appropriate.

The expanded passage portion 21 b is provided in the hot water supply passage 21 in order to increase its volumetric capacity, and the flow speed of the hot water that is being mixed is lowered by providing the junction C in that expanded passage portion 21 b. Due to this, the hot water supply passage 21 becomes substantively longer, and the hot water to which heat has been supplied and the cold water are mixed together sufficiently well in the expanded passage portion 21 b, whereby it is possible to supply hot water at a uniform temperature. Moreover, the supplied hot water temperature sensor 28 is able to detect the temperature of this hot water that has been sufficiently well mixed. Accordingly, it is possible to perform appropriate hot water supply temperature control on the basis of the output hot water temperature, the hot water supply temperature, and so on.

Furthermore, since the second bypass passage 22 is built as a conduit member whose diameter is smaller even than that of the conduit member that constitutes the passage portion 21 a, accordingly, due to the higher pressure of the water flowing in the second bypass passage 22, it is possible to prevent reverse flow of the hot water flowing in the expanded passage portion 21 b back into the second bypass passage 22 at the junction C. Moreover, the flow resistance is reduced due to the provision of the expanded passage portion 21 b, and this is advantageous for providing supply of hot water at a high flow rate, and also the flow speed is reduced, which is advantageous from the point of view of suppressing erosion.

On the other hand, if room heating operation is already being performed when hot water supply operation starts, and if on the basis of the set hot water supply temperature and the output hot water temperature and so on the control unit 5 determines that room heating operation and hot water supply operation can both be performed simultaneously, then the distribution ratio of the first distribution valve 15 is changed so that room heating operation and hot water supply operation are both performed simultaneously. Accordingly the convenience is enhanced, since it is possible to employ both room heating and hot water supply at the same time. It should be understood that, if the flow rate demanded for hot water supply is high or the like so that the control unit 5 does not determine that both room heating and hot water supply can be performed simultaneously, then hot water supply operation is preferentially performed, and, when utilization of that hot water supply has ended, the first distribution valve 15 is adjusted and the system returns to performing room heating operation.

Apart from the above, it would be possible for a person of ordinary skilled in the art to implement various changes and/or additions to the embodiment of the present invention described above without any deviation from the gist of the present invention, and accordingly the present invention is to be considered as including all such variant embodiments thereof. 

1. A heating device with hot water supply function, comprising: a combustion means; a main heat exchanger; a circulation passage connecting the main heat exchanger to a heating apparatus; a circulation pump provided in the circulation passage; a bypass passage that branches off from the circulation passage and bypasses the heating apparatus; a secondary heat exchanger, provided in the bypass passage; a cold water supply passage for supplying cold water to the secondary heat exchanger; a hot water supply passage for supplying hot water to which heat has been supplied by the secondary heat exchanger; a hot water supply bypass passage that connects the cold water supply passage to the hot water supply passage, bypassing the secondary heat exchanger; a flow adjustment means for adjusting a flow rate in the hot water supply bypass passage and thereby controlling the temperature hot water to be supplied; and an expanded passage portion of the hot water supply passage, whose diameter is expanded from an intermediate portion of the hot water supply passage to a downstream end of the hot water supply passage.
 2. The heating device with hot water supply function according to claim 1, wherein the hot water supply bypass passage is connected to the expanded passage portion.
 3. The heating device with hot water supply function according to claim 1, wherein a diameter of the hot water supply bypass passage is smaller than a diameter of the hot water supply passage on an upstream side than the intermediate portion thereof.
 4. The heating device with hot water supply function according to claim 1, wherein a temperature detection means is provided in the hot water supply passage on the upstream side than the intermediate portion thereof.
 5. The heating device with hot water supply function according to claim 1; wherein a distribution means is provided in a branching portion where the bypass passage branches off from the circulation passage; and the distribution means is capable of adjusting its distribution ratio, so that it becomes possible to perform only room heating operation, or only hot water supply operation, or simultaneous room heating and hot water supply operation. 